Gross Anatomy - Exam 4 Flashcards
What are the subdivisions of the GI system
Foregut, midgut, hindgut
Plane at T9 vertebral level
Xiphisternal plane
Plane at L1 vertebral level
Transpyloric plane
Plane at L3 vertebral level
Subcostal plane
Plane at L4 vertebral level
Supracristal plane
Plane at L5 vertebral level
Transtubercular plane
Plane at S2 vertebral level
Interspinous plane
Where is the suprapubic plane located?
No vertebral level. Located below S3
Where does the terminal portion of the esophagus enter the abdomen and stomach?
Abdomen at T10. Stomach at T11.
Where is the stomach located?
Tip of 8th costal cartilage at T11
Where is the pylorus located?
½ inch from midline at transpyloric plane (L1)
What are the parts of the stomach?
(4) Cardia, fundus, body, pyloric part
What is the name of the fold located in the stomach?
Gastric rugae
What are the curvatures of the stomach?
Greater curvature and lesser curvature
Intraperitoneal vs. retroperitoneal
Intraperitoneal – structures within the peritoneum, mobile
Retroperitoneal – structures outside the peritoneum, fixed location
What are the four parts of the duodenum and location?
1st part – anterior to posterior at L1
2nd part – fixed against body wall at L2
3rd part – fixed against body wall at L3
4th part – fixed against body wall at L2
Which part(s) of the duodenum are intraperitoneal? Which are retroperitoneal?
1st part – intra
2nd, 3rd, and 4th – retro
What are the folds within the small and large intestine called?
Plica circulares
What are the projections located within the duodenum and where do they drain?
Minor duodenal papilla – insignificant amount of pancreas
Major duodenal papilla – liver, gallbladder, and pancreas
Cystic Duct + Common Hepatic Duct = Common Bile Duct
Common Bile Duct + Main Pancreatic Duct = Major Duodenal papilla
How can you tell the difference between jejunum and ileum?
Jejunum – prominent plica circulares
Ileum – few/flattened plica circulares
Are the jejunum and ileum intra or retroperitoneal?
Intraperitoneal
Location of jejunum and ileum
Jejunum starts left of L2
Descends diagonal along root of mesentery to L5
Ends at ileocolic junction L5
How long is the jejunum? The ileum?
Jejunum – 7-8 feet
Ileum – 6-12 feet
Four characteristic features of large intestine
Taeniae coli
Haustra (segmental appearance)
Epiploic appendices
Plica semilunaris
What forms the appendix?
3 teniae coli coming together
Cecum and appendix location
Begins at transtubercular plane (L5)
Lies at interspinous plane (S2)
Ascending colon location
Extends from cecum to transpyloric plane (L1)
Transverse colon location
Begins right colic flexure (transpyloric plane L1)
Ends at left colic flexure T12
Descending colon location
Extends from T12 to transtubercular plane L5
Sigmoid colon location
Begins at transtubercular plane L5
Ends midline below interspinous plane S2
Order of pathway thru large intestine
Cecum/appendix > ascending colon > transverse colon > descending colon > sigmoid colon > rectum
What are the changes in direction in the large intestine?
Right colic/hepatic flexure
Left colic/splenic flexure
Determine whether each portion of the large intestine is intra or retroperitoneal
Cecum – intra
Ascending colon – retro
Transverse colon – intra
Descending – retro
Sigmoid colon – intra
Rectum – retro
What are the fat droplets on the intestine called?
Omental/epiploic appendices
Where is teniae coli NOT present in the large intestine?
Rectum
Location of upper and lower borders of the liver
Upper – T9
Lower – L3 on right, T9 on left
Four anatomical lobes of liver
Right, left, quadrate, caudate
What structures are found in the liver?
- Ligamentum venosum
- Ligamentum teres hepatis (aka round ligament)
- Porta hepatis (hepatic portal vein, proper hepatic artery, common hepatic duct)
Functions of liver
Synthesize plasma proteins
Production of bile
Detoxification
Glycogen storage
Production of hormones
What separates right and left lobes of liver?
IVC
What separates left and caudate lobes of liver?
Ligamentum venosum
What separates left and quadrate lobes of liver?
Ligamentum teres hepatitis/round ligament
What is in the portal triad? Where does it enter?
Portal triad: hepatic portal vein, proper hepatic artery, common hepatic duct
Enters liver at porta hepatis
Ligamentum venosum developmental origin
Ductus venosus
Ligamentum teres hepatis developmental origin
Umbilical vein
Name and location of the 4 parts of the pancreas
Head of pancreas – L2 (in ‘C’ of duodenum)
Neck, body, and tail – L2, L1, T12 (ends in spleen hilium)
Determine whether each part of pancreas is intra or retroperitoneal
Head, neck, and body – retro
Tail – intra
Which parts of the pancreas are considered “ventral pancreas”? Which parts are “dorsal pancreas”?
Head and neck – ventral
Body and tail – dorsal
What structures enter the pancreas connecting with major or minor duodenal papilla?
Main pancreatic duct (MOSTLY) to major duodenal papilla
Minor pancreatic duct to minor duodenal papilla
Gallbladder location
Tip of 9th costal cartilage on right at transpyloric plane (L1)
What drains the gallbladder?
Cystic duct into common bile duct
What are the arterial vasculatures and location?
- Celiac axis – T12
- Superior mesenteric – L1
- Renal (paired) – L2
- Gonadal (paired) – L2/L3
- Inferior mesenteric – L3
Branches of celiac artery
(3) Left gastric, common hepatic, splenic
Branches off common hepatic artery
(2) Proper hepatic and gastroduodenal arteries
Branches off proper hepatic arteries
(3) Right gastric, left hepatic, and right hepatic
Branch off right hepatic artery
Cystic artery
Branches off gastroduodenal artery
(4) Supraduodenal, right gastroepiploic, and anterior and posterior superior pancreaticoduodenal
Branches off splenic artery
(3) Pancreatic, short gastric, left gastroepiploic
Structure that surrounds greater curvature of the stomach
Greater omentum
What arterials anastomose at the greater curvature? What about the lesser curvature?
Greater: right and left gastroepiploic arteries
Lesser: right and left gastric arteries
What are the branches off the superior mesenteric artery?
- Anterior and posterior inferior pancreaticoduodenal
- Jejunal mesenteric
- Ileal mesenteric
- Ileocolic
- Right colic
- Middle colic
How to tell between the jejunum and ileum based on vasa recta and arcades
Jejunum: vasa recta are long and spread; arcades are large and fewer in number
Ileum: vasa recta are short and compact; arcades are small and layered
What are arcades?
Anastomotic loops located in small intestine
What are the branches off inferior mesenteric artery
(3) Left colic, sigmoid, and superior rectal arteries
Tributaries of portal vein
(2) Superior mesenteric and splenic veins
What are the portacaval anastomoses?
Esophageal veins, rectal veins, para-umbilical veins, and retroperitoneal veins (colic and splenic veins with body wall veins)
What are issues with using the anastomoses paths? Which vein is most life threatening if it breaks?
Blood is not clean and overworks these veins
Varacies: stretching or enlargement of vein
Esophageal vein is most life threatening
What germ layers are responsible for GI system
Mesoderm and endoderm
The GI is a hollow tube extending from ___ to the ___.
Buccopharyngeal membrane (future mouth); cloacal membrane (future anus)
Name of membranes resulting in future mouth and anus
Mouth: buccopharyngeal membrane (breaks down at 3rd week of development)
Anus: cloacal membrane (breaks down at 7th week of development)
Germ layer of epithelial lining of organs? Muscular walls and serous coats?
Endoderm – epithelial lining
Mesoderm – muscular walls and serous coats
What is the name of the cavity where the GI develops? What does it turn into?
Cavity: intraembryonic coelom
Future: peritoneal cavity
What are the subdivisions of the developmental digestive system?
Foregut, midgut, and hindgut
What is the arterial supply of the foregut?
ALL celiac artery
Esophagus (overlaps): celiac and esophageal arteries
Pancreas (overlaps): celiac and superior mesenteric arteries
(Duodenum parts 1 and 2)
Spleen is not a GI organ but also celiac artery
What is the parasympathetic innervation of the foregut?
Vagus/Cranial n. X
What is the arterial supply of the midgut?
ALL superior mesenteric
(Duodenum parts 3 and 4)
What is the parasympathetic innervation of the midgut?
Vagus/Cranial n. X
What is the arterial supply of the hindgut?
ALL inferior mesenteric
What is the parasympathetic innervation of the hindgut?
S2, S3, S4 aka. Pelvic splanchnics
What structures are part of the foregut?
(7) Esophagus, stomach, duodenum parts 1 and 2, liver, gallbladder, and pancreas
What structures are part of the midgut?
(8) Duodenum parts 3 and 4, jejunum, ileum, appendix, cecum, ascending colon, and transverse colon
What structures are part of the hindgut?
Descending colon, sigmoid colon, and rectum
Explain development of stomach
First visible at 4th week of development
Suspended from dorsal wall by DORSAL MESOGASTRIUM
Rotates 90 degrees clockwise, trapping part of right side of INTRAEMBRYONIC COELOM posterior to stomach/omental bursa
Explain development of duodenum part 1 and 2
Gets C shape when stomach rotates
What occurs at the 6th, 9th, and 12th week of development in the liver?
6 – hematopoiesis occurs
9 – liver reaches max proportional size
12 – bile formation begins
What does the liver develop from?
From hepatic bud as an outgrowth of 2nd part of duodenum
What does the gallbladder develop from
As an outgrowth from the hepatic bud
Where does the pancreas develop from?
Ventral bud – outgrowth of hepatic bud -> HEAD AND NECK
Dorsal bud – outgrowth of 2nd part of duodenum -> BODY AND TAIL
** think on all fours like dog
What becomes a source of major drainage of the adult pancreas?
Duct of ventral bud
Explain development of midgut
Elongates along an axis around superior mesenteric artery via VITEILLOINTESTINAL DUCT
Rotates 270 degrees
Explain development of hindgut
Supplied by inferior mesenteric artery
Cloacal membrane separates and breaks open
What forms the bony pelvis?
(3) Ilium, ishium, and pubis
What is the “wing” of the pelvis?
Ala
What are the bony landmarks of the anterolateral wall?
- Iliac crest – most superior aspect
- Iliac tubercle – bony, widest part of ala
- ASIS – most anterior component of pelvis
- Pubic tubercle – most inferior component
Why is the pelvis tilted?
Tilted forward because we walk upright and mimics locomotion
Who has a smaller inlet? Wider? (M/F)
Male has smaller (90 degrees or less)
Female has wider for ample room to deliver (100 degrees or more)
What structures are formed by the fusion of aponeuroses on the lateral wall muscle?
Linea alba, linea semilunaris, inguinal ligament, and tendinous intersections
What are the abdominopelvic regions?
Right hypochondriac, epigastric, left hypochondriac
Right lumbar, umbilical, left lumbar
Right iliac, hypogastric, left iliac
What are the abdominopelvic quadrants
Right upper, left upper
Right lower, left lower
What are the fascia of the abdominal wall?
Camper’s fascia (fatty, more membranous layer)
Scarpa’s fascia (membranous)
What are the muscles of the abdominal wall?
- External oblique
- Internal oblique
- Transversus abdominus
- Rectus abdominus
Function of abdominal muscles
Assist in respiration
Increase thoracic/abdominal pressure
Keep abdominal contents in place
Maintain posture
Flexion of trunk
What is the Valsalva maneuver?
Forced expiration against a closed glottis
Affects venous return, CO, arterial pressure, HR
Used to correct abnormal heart rhythms (supraventricular tachycardia and stimulate vagus n.)
What is defecation syncope
Elevate arterial pressure, bradycardia, decrease BP, decrease blood to brain (leads to cardiac event/failure)
External oblique origin and insertion
O: ribs 5-12
I: anterior ½ of iliac crest, linea alba, and pubic crest and tubercle
External oblique innervation
T7-T12 and L1
External oblique function
Flexion of trunk
Lateral flexion
Rotation of vertebral column (opposite/contralateral side)
Internal oblique origin and insertion
O: thoracolumbar fascia, ant 2/3 of iliac crest, and lat 2/3 of inguinal ligament
I: ribs 10-12, linea alba, and pubis (conjoint tendon)
Internal oblique innervation
T7-T12 and L1
Internal oblique function
Lateral flexion
Rotation (same/ipsilateral side)
Transversus abdominis origin and insertion
O: thoracolumbar fascia, Ant 2/3, Lat 1/3 of inguinal ligament, and lower 6 costal cartilages
I: linea alba and pubic crest (conjoint tendon)
Transversus abdominus innervation
T7-T12 and L1
Transversus abdominus function
Compress abdominal contents
Rectus abdominus origin and insertion
O: pubic symphysis
I: xiphoid process and costal cartilages 5-7
Rectus abdominus innervation
T7-T12
Rectus abdominus function
Flexion of trunk
What is the rectus sheath?
Aponeurosis of 3 flat muscles (external, abdominal, and oblique muscle)
Landmarks of rectus sheath
Linea alba (xiphoid to pubic symphysis)
Linea semilunaris (subcostal margin to inguinal ligament)
Arcuate line (1/3 distance from umbilicus to pubic crest)
What structures are above the arcuate line
Anterior rectus sheath (external oblique and ½ internal oblique)
Posterior rectus sheath (1/2 internal oblique and transversus abdominus)
What structures are below arcuate line?
Anterior rectus sheath (external oblique, internal oblique, transversus abdominus)
NO POSTERIOR RECTUS SHEATH only transversalis fascia
What arteries come off aorta in anterior abdominal wall?
10th and 11th posterior intercostal arteries
Subcostal artery
What arteries come off internal thoracic artery in anterior abdominal wall?
Superior epigastric and musculophrenic arteries
What artery comes off external iliac artery in anterior abdominal wall?
Inferior (deep) epigastric artery
What artery comes off femoral artery?
Superficial epigastric (runs thru superficial tissues/fascia)
What are the nerves of the anterior wall?
Thoracoabdominal (T7-11)
Subcostal (T12)
Iliohypogastric (L1)
Ilioinguinal (L1)
Where do the T7-T12 nerves lie?
Between internal oblique and transversus abdominis and penetrates rectus
Sensory distribution of anterolateral wall generalizations
T7-9 - above the umbilicus
T10 – umbilicus
T11, T12, L1 – below umbilicus
Where do the testes develop, pass thru, and enter?
Develop: lumbar area attached to gubernaculum on inf. Pole
Pass: thru inguinal canal and pick up muscle/fascial layers from ant. Wall
Enter: scrotum
What structures are derived from external oblique?
Inguinal ligament (ASIS to pubic tubercle)
Superficial ring
What is the inguinal canal?
Passageway thru abdominal wall to scrotum for testes and spermatic cord
What is a hernia?
Protrusion of parietal peritoneum and/or viscera thru opening from cavity which they belong
What are the types of hernias?
femoral, direct, indirect
Describe femoral hernia
Most common in females at femoral triangle/canal
Describe direct hernia
Most common over 50 years old, bulges at superficial ring, and medial to inferior epigastric a.
Describe indirect hernia
Congenital, most common under 50 yo, begins at deep inguinal ring, lateral to inferior epigastric a.
What is Hesselbach’s Triangle?
Site of direct hernia
Borders: inguinal ligament, inferior epigastric artery, lateral border of rectus abdominis
What are the visceromotor targets?
(3) Cardiac muscle, smooth muscle, and glands
Function of parasympathetics in abdomen
Stimulates peristalsis
Where do parasympathetic fibers originate?
CN X and pelvic splanchnic S2-4
Function of sympathetics in abdomen
Decrease blood flow in viscera/inhibit digestion
Where are the sympathetic preganglionic cell bodies for GI located?
Cell body #1 – IML T1-L2
Where are the sympathetic cell bodies for upper GI to diaphragm?
IML T1-6
Where are sympathetic cell bodies for GI to rectosigmoid junction?
T7-11
Where are the sympathetic cell bodies for rectum/anal canal?
T12-L2
Where does the sympathetic chain run?
Chain ganglia runs from base of skull to coccyx
What are the splanchnic nerves of the abdomen?
- Greater T5-9
- Lesser T10-11
- Least T12
- Lumbar L1-4
Where does the anterior vagal trunk come from? What does it innervate/supply?
From CN X
Comes from left vagus and becomes anterior vagal trunk when is passes thru esophageal hiatus
Supplies anterior surface of stomach and sends branch to liver
Where does the posterior vagal trunk come from? What does it innervate/supply?
From CN X
Come from right vagus nerve
Supplies posterior stomach and sends branch to celiac plexus
What are the pelvic splanchnics? Where do they come from? What does it innervate/supply?
Parasympathetics to hindgut
Cell body in IML L1/L2
Supplies descending and sigmoid colon rectum
Exit as preganglionic
What do pelvic splanchnics travel with?
Spinal nerves S2-S4
What are the sympathetic ganglia of the abdomen? What fibers synapse here?
Celiac ganglion – greater splanchnics (T5-9)
Superior mesenteric ganglion – lesser splanchnics (T10-11)
Aorticorenal ganglia (paired) – least splanchnics (T12)
Inferior mesenteric ganglion – lumbar splanchnics (L1-4)
What are the autonomic plexi?
(5) Celiac, superior mesenteric, renal, inferior mesenteric, hypogastric (pelvis)
What do thoracic and lumbar splanchnic nerves contain?
Preganglionic sympathetic fibers
Synapse on prevertebral ganglia in abdomen – contribute to plexi
The postganglionic sympathetic fibers innervate targets
How do preganglionic parasympathetic fibers from CN X and pelvic splanchnics travel?
Thru plexi or directly to viscera
DO NOT synapse in plexus
Fibers travel to viscera of wall where ganglia is present to synapse
Postganglionic fibers project to targets
What do the autonomic plexi of gut consist of?
Postganglionic sympathetic fibers and preganglionic parasympathetic fibers
Visceral vs. Parietal Pain
Visceral pain: general visceral afferent (GVA)
Parietal pain: general somatic afferent (GSA)
What type of neuron for GVA and GSA?
Pseudo unipolar, sensory neuron
Describe GVA fibers/viscerosensory
Nociceptors (noxious stimuli)
Cell body in DRG
Sensitive to stretch, ischemia and inflammation
Insensitive to cutting or burning sensations
How do GVA fibers interact with ANS?
It is NOT part of but distribute WITH ANS
Sympathetics run w/ splanchnics (greater, lesser, least, lumbar)
Parasympathetics run w/ S2-4, CN X
What is visceral pain and examples?
Vague, poorly localized pain
E.g. intestinal obstruction, cholecystitis, and early appendicitis
Describe GSA fibers
Cell bodies in DRG
Info includes pain, touch, temp
Nociceptors (noxious stimuli)
GSA fibers follow what?
Somatic innervation
Carried in all spinal nerves except C1
What is parietal pain and example?
Sharp, well localized pain, pt can tell you where it hurts
E.g., acute appendicitis
What is referred pain?
Pain perceived to be in unrelated area
Sensory picked up by viscera
Transmitted by ANS fibers/nerves
Perceived as originating from somatic structure but in reality, it is from visceral fibers
Ascending sensory pathway
Nociceptor in viscera > afferent fibers relay sensory info in splanchnics > enter sympathetic trunk > join spinal nerve via white rami > ascend to cortex (post central gyrus) to interpret pain
What is Convergence Ho?
Collaterals from visceral afferents synapse on somatosensory cell bodies
Pain interpreted as coming from “somites” (e.g., skin/muscle)
What is an angina?
Pain from heart disease
Pain/squeezing/pressure behind sternum
Usually radiates down left arm but sometimes in neck, jaw, TMJ
Angina pathway for referred pain
- Afferent fiber from heart enters sympathetic chain thru thoracic cardiac n. or cervical cardiac n.
- Same segments receive GSA input from dermatomes of chest and arm
- Post cells GSA can be activated by collateral GVA fibers from heart
- Cortex interprets pain as if its from chest even if its from heart
What are the three regions of the posterior abdominal wall?
Above 12th rib, below 12th rib and iliac crest, and below iliac crest
What are the two sides of the posterior abdominal wall
Divided by aorta and IVC
What are the contents of the posterior abdominal wall?
Kidneys and ureters, suprarenals (adrenal glands), spleen, and BVs and nerves
What forms the iliopsoas?
Psoas major and iliacus
Function of psoas major
Flexion of femur
Function of iliacus
Flexion of femur
Function of quadratus lumborum
Lateral flexion of vertebral column
Function of psoas minor
Not always present, but (weak) flexion of lumbar vertebral column
Where are hernia of Morgagni and Bochdalek located? Which is more life threatening?
Hernia of Morgagni: anterior and retrosternal
Hernia of Bochdalek: posterolateral, most life threatening
Surface anatomy and location of spleen
Upper pole – T10
Hilum - T12
Lower pole – T12
Location: parallels 10th rib
What organs do the spleen contact?
(4) Stomach, pancreas, kidney, and large intestine
Can you palpate for spleen?
Normally not! Unless enlarged 3-5x normal
Splenomegaly – enlargement of spleen (e.g., due to mono)
Surface anatomy of kidney and distance from midline
Upper pole – T12, 1 inch
Hilum – L1, 1.5 inches
Lower pole – L3, 3 inches
Which is higher: left or right kidney
Left kidney is usually ½ inch higher bc liver is above right
Are kidneys intra or retroperitoneal?
Retroperitoneal
Surface anatomy of ureter
Begins at hilum of kidney @ L1
Travels 1.5 inch from midline until it reaches bladder
What are the unpaired visceral branches of the abdominal wall?
(3) Celiac, superior mesenteric, and inferior mesenteric arteries
What are the paired visceral branches of the abdominal wall?
Renal, gonadal, and suprarenal arteries
What are the suprarenal arteries? What do they come off of?
- Superior suprarenal off inferior phrenic a.
- Middle suprarenal off aorta
- Inferior suprarenal off renal a.
What are the paired parietal/body wall branches of the abdominal wall?
Inferior phrenic and lumbar aa.
What veins come off IVC in abdominal area?
*only need to know these three
1. Hepatic veins
2. Right suprarenal vein
3. Left/right gonadal veins
What are the nerves of the posterior abdominal wall?
1.2 Subcostal n.
2. Iliohypogastric n. (more superior n.)
3. Ilioinguinal n. (more inferior n.)
4. Lateral femoral cutaneous n.
5. Genitofemoral n.
6. Femoral n.
7. Obturator n.
What is the vertebral origin of the subcostal n?
T12
What is the vertebral origin of the iliohypogastric n?
L1
What is the vertebral origin of the ilioinguinal n.?
L1
What is the vertebral origin of the lateral femoral cutaneous n.?
L2, L3
What is the vertebral origin of the genitofemoral n.? What are the branches of this n? What do each branch supply?
L1, L2
1. Genital branch – cremaster
2. Femoral branch – sensory on thigh
What is the vertebral origin of the femoral n.?
L2, L3, L4
What is the vertebral origin of the obturator?
L2, L3, L4
Name of membrane that encloses vasculature of intestines (e.g. arcades and vasa recta)
Mesentery proper/peritoneal ligaments
Which week does the stomach become visible in development
4th week
When does the buccopharyngeal membrane break down and what does it become
Breaks down at 3rd week
Mouth
When does the cloacal membrane break down and what does it become
Breaks down at 7th.
The anus
Three places we can get kidney stones
Uretoropelvic junction
Ureterovesical junction
Crossing of iliac a
What do the branches of L1 pierce?
Branches: iliohypogastric and ilioinguinal
Penetrate/pierce thru internal oblique around ASIS, then continue to run between internal and external obliques
